1. Field of the Invention
The present invention relates generally to asynchronous transfer mode (ATM) networks, and more specifically to the reservation of network resources in an ATM network in response to users' requests.
2. Description of the Related Art
Japanese Laid-Open Patent Specification Hei-6-30021 discloses time-scheduled communications in a switched network in which ATM switching nodes individually perform reservation of a bandwidth according to user's reservation requests by storing reservation requests in memory and monitoring the stored requests in order to establish a connection at requested time of day if network resource is available. After the connection is established, the ATM switches monitor the stored request in order to release it at the expiry of the reservation.
Since the prior art resource reservation is implemented individually on a per-node basis and no facility is available to link the reservation data between ATM switches, network reservation cannot be performed on an end-to-end basis. In addition, network resource reservation is attempted at the very instant at which the scheduled communication begins. Although the prior art is provided with means for rejecting some calls if they occur during a predetermined interval prior to the scheduled communication, there is some degree of uncertainty to satisfy the reservation request at the beginning of the scheduled communication. Furthermore, if the ATM switches fail to satisfy a reservation request at the beginning of the scheduled communication, there is no fallback procedure for continuing the search for the requested network resource.